R12制冷剂的选择与替换方案毕业设计【参考】.docx

摘 要由于传统制冷剂（CFCs、HCFCs）对臭氧层存在破坏作用，属于温室效应气体，并且对环境有破坏作用，已经或者即将在全球范围内禁用，寻找合适的新型环保替代制冷剂已成为当今空调制冷行业的一个热点问题。目前R12、R22等传统制冷剂已有多种替代方案，但各有其优缺点，因此国内外正在积极研发新一代的替代物。本文的主要工作是寻找一种能直接充灌的R12替代工质。本文从环保要求出发，按照热力学相似原则，对多种纯质工质进行了饱和蒸气压分析，并以R290和R1270作为基础组元，根据优势互补理论，筛选出R290/R227ea、R1270/R227ea、R290/R134a/R227ea三种新型混合制冷剂组合。在对实际制冷循环进行分析简化后，建立了理论循环计算模型，并以REFPROP8.0为依据计算混合物热物理性质并编制仿真程序，对三种混合制冷剂的不同配比进行计算分析。最后按照一定原则，提出了三种最优配比制冷剂混合物（R290/R227ea:0.9/0.1）、（R1270/R227ea:0.9/0.1）和（R290/R134a/R227ea：0.85/0.05/0.1）作为R12直接充灌替代物。为了进一步了解所提出的新制冷剂的实际性能，对三种新提出的混合制冷剂进行了变工况分析。通过与被替代制冷剂R12的比较与分析，发现所提出的三种新型环保混合制冷剂具有良好的环保性能，与被替代制冷剂性能相近，达到了最初对替代制冷剂的要求。关键词：混合替代制冷剂，R01(R290/R227ea)，R02(R1270/R227ea)，R03(R290/R134a/R227ea)，变工况分析ABSTRACTFor the traditional refrigerants (CFCs, HCFCs) have been or will be phased out because of their disadvantages on environmental protection the development of the new refrigerant is under progress. Many substitutes have been proposed, but no one perfectly replaces traditional refrigerants like R12 or R22 now. New generation of alternatives is being investigated worldwide. The purpose of this dissertation is to find a new environmental refrigerant which can be directly used in the refrigeration equipment of R12.Based on the requirements of environmental protection and the principle of thermodynamic similarity, R290 and R1270 were employed as the main component. Three kinds of mixtures were selected as the new alternative refrigerants. Based on the simplifiedactual refrigeration cycle，a computational model was created to establish a theoretical cycle, and REFPROP8.0 was used to calculate the mixture of thermo physical properties, the mixture of two different refrigerants ratio calculated and analyzed. According to the principle, optimization on mixture ratio is conducted and refrigerant mixture R290/R227ea(0.9/0.1), R1270/R227ea(0.9/0.1) and R290/R134a/R227ea (0.85/0.05/0.1) were determined as the alternative to R12 used in existing equipment at last.The variable conditions of three new r